My, how times have changed: A woman, Hillary Clinton, is a serious contender to be the next U.S. president. But maybe they haven't changed all that much: According to the National Center for Women & Information Technology (NCWIT), there has been an astounding 70 percent decline in the number of incoming undergraduate women choosing to major in computer science between 2000 and 2005.

These numbers indicate a dramatic shift downward in women in high tech, but they don't tell us why. It could be that employment opportunities in high tech haven't gotten better for women since the 1980s, when females first started to break into the technology field. Or perhaps something deeper is going on: Perhaps women have decided that high tech is not a career path worth pursuing and are looking elsewhere.

Despite major efforts by the National Science Foundation, IEEE, ACM, and others in the 1980s to encourage more women to enter the computer science and engineering professions, the latest numbers gathered by NCWIT show little progress. Although women hold 51 percent of professional positions in the United States, they hold only 26 percent in IT and just 13 percent of C-level positions in Fortune 500 technology companies. Statistics from the federal government show a similar pattern.

And there's not much hope for a new wave of women to step into these positions. Although girls took 56 percent of all Advanced Placement (AP) tests in high schools — the tests typically targeted by college-bound youths — only 15 percent of AP computer science test-takers were girls.

Research by Stanford University professor Shelley Correll indicates psychological pressure keeps many women from pursuing such careers, especially at the executive level. Her research indicates that women are often aware of the stereotypes about their gender, which causes them to judge their own abilities by unreasonably high standards, in order to prove the stereotypes untrue. That leads some women to pull back from leadership positions when their instincts clash with those stereotypes.

Five who've succeeded in the boys' clubSurveys tell you the pattern, but they don't provide the insight, much less the road map. So InfoWorld interviewed five women who have attained lofty positions in high tech to uncover what propelled them into the field and what has kept them successful in the IT boys' club over the years.

Tamara Casey, CEO of 4DK, is probably best known for her 14 years as vice president of technology strategy, architecture, and research at Nextel Communications. Today she is CEO and co-founder of 4DK, a company whose middleware appliance connects communications networks.

Susan Major is the managing partner for the Global Technology Practice at DavenportMajor, an executive search firm. Earlier in her career, as an executive at Motorola, she introduced two-way radios, cellular handsets, and the first Motorola PDA.

Beatriz Infante is the CEO of VoiceObjects, a provider of adaptive self-service phone portal solutions. She has also been CEO of Aspect Communications and senior vice president of Oracle's Application Server division.

Lucy Sanders is the CEO and co-founder of NCWIT and is executive-in-residence for the Atlas Institute, a think tank for communications and computer technology at the University of Colorado at Boulder. She has also been an executive AT&T Bell Labs, Lucent Bell Labs, and Avaya Labs, specializing in systems-level software and solutions.

Claudine Simson is CTO of semiconductor maker LSI, and previously was CTO at Motorola.

Don't be afraid to wield powerCorrell's study at Stanford showed that the core issue inhibiting women from using power is that stereotypes exist — not that women believe they are true. "I don't have to actually believe the stereotype that men are better at math than women for it to affect my own sense of whether I am good enough at math to continue on a career that requires mathematical ability. Instead, if I know or suspect that others hold this stereotype, I may come judge my own mathematical performance by a harsher standard, expecting that others might not accept me as mathematically competent," she said.

Sanders said in light of studies such as Correll's, women need to be encouraged to say, "'Yes, you can be CTO or CEO,' and not to back off. If that happens, we might see more women assuming those [executive-level] positions."

While the Stanford research may explain why some women shy away from taking on senior leadership roles, Infante said that women have to get over that fear. "I am who I am, and I am very good at what I am," she said. If you are, as she is, a "top ranked" engineer working on a project, the role carries a "great deal of power" that you should exercise, she added.

The other four women execs agreed with Infante that, at the end of the day, it's all about the bottom line and any executive — male or female — has to be unafraid to wield power in order to succeed. "Some people think 'power' is a dirty word. I think that power — if used well for a corporation and for people — is very beneficial," Sanders said.

The perception dilemmaHowever, women face unique problems when they assert themselves, Casey noted. "You have to be assertive to get people to pay attention and maybe aggressive, but then you become perceived as unladylike — and men get irritated by that," she said. "When you are direct and businesslike and speak your mind and tell it like it is and have all the attributes that you admire in a male executive, you get labeled as a troublemaker or a pain in the you-know-what," she added.

Women still have to walk a fine line between being too strong versus looking too soft, Major concurred. "It's different for men. They have no issues being [themselves] around women," she said. By contrast, Casey said, women have to be "insanely perfect and PC [politically correct] and savvy to survive in the corporate culture."

Simson noted a softer personal style has a lot to do with her success and in getting results — relying on her technical qualifications is insufficient. "My style is not abrasive. I work with people and lead them, but I don't tell them what to do. You have to have the ability to collaborate with people."

In fact, a change in business culture to favor teams and collaboration over rigid hierarchies should work in women's favor, Major said. "It's [no longer the] old-school dictatorial style" for men or women, she said, and the current collaborative style fits in with how women more typically work. She added, "Women tend to collect data and take more time, be more collaborative, and make sure that everyone has been heard."

And women should not let style differences between themselves and men — whatever their origins — get in the way. "A solid work ethic outweighs any personality issues," Casey said. "People who are successful are true to themselves, have a solid work effort, and produce — outweighs any personality issues," she added.

Act like a man?Infante doesn't buy the argument that women have to navigate a double standard. Her advice is that women should be unafraid to behave in business as men do, such as wielding their power as a male executive would. "Self-confidence shows, and people are trained to recognize that in others," she said. For her, the real problem comes when "women are hesitant about the use of power." That signals weakness, which undermines their leadership more than the fact that they are women.

Infante acknowledges that "acting like a man" goes against how most women are raised, which is to be shyer and to want to please. But that just won't work in business. "Business is a lot less about the softer self," she said. "Our education system creates passivity in girls and encourages activity in the boys. [Yet] in business you have to be aggressive," Infante added.

From years of working alongside Larry Ellison at Oracle, Infante had a front-row seat to seeing how an aggressive leader operates. "It's not a secret that Larry does not treat people nicely. I am not saying that is a good thing but … business is ultimately about competing. If you are out there and aren't 120 percent in your ability to defeat the opposition, then you will fail. This is where Larry has been very successful. He asks every day, 'What have you done to win today and what have you done today to defeat the competition?'"

Still, Infante admits that a woman could not easily act as tough as Ellison. "If a woman treated people like Larry treated people, people would focus more on the fact that she is not being kind and gentle, but with Larry, they say, 'Oh well, that is the way Larry is.'"

Ellison may be an extreme case, and women don't need to ape male behavior to use their power, Simson advised. She warned young women not to try to be something they are not. "Retain your personality. Being successful is not dependent on being harsh. Be strong, know what you want. Competency is what is valued and what commands respect. Respect does not come because you bullied," she said.

How to climb to the topDespite the perception issues that can make it harder for women to be seen as leaders, the path to the top in IT doesn't appear to differ from the path to the top in any industry.

"Women don't have to be groundbreakers, just the best ones for the job," Major said. The fact is that more women now have great track records, so there is a pool of women in the industry who have made it easier for future generations.

Infante said being a woman may actually help. In her case, she said she stood out a bit more in a room full of people all equally as good. "I think my being a woman has been neutral to slightly positive, but no negatives, no barriers," she said. Infante was also helped by having her formative career occur at Hewlett-Packard, whose culture was "very egalitarian."

What's turning women away?The wireless industry turned to foreign women when it couldn't fill its ranks in the United States, taking advantage of the controversial H-1B visa program. "A lot of people were available through the H-1B from Europe and some from Asia, where there hasn't big an issue of getting women into engineering and computer science programs," Casey said. "In the U.S., it continues to be an issue."

In fact, the issue has gotten worse. In 1985, 37 percent of computer science undergraduate degree recipients were women. In 2006, just 21 percent were.

Simson said she suspects the decrease in women's enrollment in high tech is due to the stigma associated with long hours in a very demanding field with lots of economic up and down cycles. "It is associated in the minds of people as not stable," she said.

The combination of instability and demanding hours also gives women an unpalatable choice between work and family, she noted. Men can more easily make the choice to work because women still typically manage the family, even if they have careers. Women get to a certain level, then have to decide whether to pull back a bit or change their career track because of the needs of the family — or to put their husbands' careers first, Major said. "The culture hasn't changed," Simson said.

The balance issue is more acute if your goal is to be in the top executive ranks. "The price you pay as a CEO or top executive is very high, whether you are a man or a woman. It takes up a lot of personal time, a lot of effort, a lot of travel. You are watched all the time. People do not realize how much they have to give up for one of those top spots," Major said. "Companies are demanding, and they want you to put in 60-hour weeks."

At that level of demand, the choice between career and family is almost inevitable, Major said. No matter how supportive a husband might be as a partner, it's tough to find the balance, to have a family and keep up as a CEO in a man's world, she said.

Another factor that keeps women out of the tech field is that the industry's image is not compelling. "The image of computing is still a white geeky guy sitting by a terminal eating junk food," Simson said. That stereotype is misplaced, even if there are ready examples at most workplaces. "Women need to understand that full range of computing, that it requires critical thinking and problem solving in addition to programming," Simson argued.

And then there's the elephant in the room, Major said: "It's still a man's world."

Still, with all the issues that may discourage women from entering technology careers, an important fact is often lost. "It is a wonderful career," Casey said. "Computing is a powerful partner and fundamental to everything in the world today."